1. Field of the Invention
The present invention relates to a lens barrel including a plurality of movable lens frames, and an optical device including the lens barrel.
2. Description of the Related Art
A lens barrel used for an optical device, such as a digital still camera or a video camera, performs zooming and focusing by moving a movable lens frame that holds a lens in an optical-axis direction by a driving force from a drive source. For example, a voice coil motor (VCM) including a stepping motor, a magnet, and a coil is used as a drive unit (drive source or actuator) that moves the movable lens frame.
In many cases, a lens barrel typically has an actuator with a structure that does not have a self-holding force in a nonenergized state in which power (drive source) is OFF. An optical element and a movable frame holding the optical element may move in the nonenergized state by a self weight and an inertial force. Then, the movable lens may contact a mechanical end (end surface) that defines a limit of a movable range of the movable lens frame. Then, the position of the movable lens frame may be changed, and a reference position (origin position) referenced when the movable lens frame moves in an energized state may be changed. Hence, movement accuracy may be degraded. Also, loud collision sound occurs when the movable lens frame contacts the end surface. A user may feel uncomfortable with the sound.
To reduce an adverse effect on an optical system when the movable lens frame collides with the mechanical end during zooming, Japanese Patent Laid-Open No. 9-318862 discloses an optical device including a rotational lever (stopper) provided at the mechanical end, and an elastic member arranged between the mechanical end and the rotational lever.
In the optical device disclosed in Japanese Patent Laid-Open No. 9-318862, the elastic member is provided near the rotational lever to reduce the effect upon the collision of the movable lens frame with the mechanical end. When the elastic member contacts the movable lens frame, the elastic member is deformed. The contact position slightly varies every time when the contact occurs. If the optical device has a configuration that correctly detects the position of the mechanical end and detects an origin position referenced when the movable lens frame moves, the movement accuracy may be degraded. Further, since the movable lens frame does not collide with the elastic member, but collides with the rotational lever. This configuration may reduce the shock; however, it is difficult to sufficiently reduce the collision sound.